The notes made by Mathis Penn in the market hall seem to disappear whenever placing them down, or even when attempting to trade them with another player.
It makes the character placing the note down automatically emote : [puts down a small note.]
But then nothing appears in the game world, and the note disappears from the inventory in the process.
This pretty much makes the scribe service useless, since other players won't be able to see it via trade or having these notes placed around the game world.
Although it might still be a way for illiterate PCs to have Public Board forum posts made, I suppose.
Had this happen to me yesterday.